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Low specificity of scanning laser polarimetry
1Department of Strabismus and Neuro-Ophthalmology, Kantonsspital, St Gallen, Switzerland. daniel.mojon@kssg.ch
Purpose:
Scanning laser polarimetry is used to assess the peripapillary retinal nerve fiber layer. This study evaluates scanning laser polarimetry in normal subjects.
Subjects And Methods:
28 eyes of 28 normal subjects (age range 21-48 years, mean age 36.5 years) had scanning laser polarimetry (NFA-GDx, Laser Diagnostic Technologies, San Diego, Calif., USA). All subjects had normal eye examinations, refractive errors with spherical equivalents <5 D and astigmatism <2 D, normal intraocular pressures, no history of diseases affecting the visual field or nerve fiber layer, and normal white-on-white automated perimetry (Octopus 101, program G2). The mean image of three good-quality measurements with the scanning laser polarimeter was included.
Results:
36% of the normal subjects (10/28) had at least one NFA parameter outside normal (p < 0.05). The parameters most frequently found to be outside normal were symmetry (21%, 6/28) and superior ratio (17%, 5/28).
Conclusions:
Scanning laser polarimetry is often used for early detection of glaucomatous damage in glaucoma suspects. This study found a specificity of only 64% and indicates that the actual selection of parameters is not adequate. Especially the parameters symmetry and superior ratio should be reevaluated in order to achieve a higher specificity.